U.S. patent application number 15/071534 was filed with the patent office on 2016-07-07 for heat pump, small power station and method of pumping heat.
The applicant listed for this patent is Efficient Energy GmbH. Invention is credited to Oliver Kniffler, Holger Sedlak.
Application Number | 20160195314 15/071534 |
Document ID | / |
Family ID | 39358078 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160195314 |
Kind Code |
A1 |
Sedlak; Holger ; et
al. |
July 7, 2016 |
HEAT PUMP, SMALL POWER STATION AND METHOD OF PUMPING HEAT
Abstract
A heat pump includes a first portion for evaporating a working
fluid at a first pressure, for compressing the evaporated working
fluid to a second, higher pressure, and for liquefying the
compressed working fluid within a liquefier, and a second portion
for compressing liquid working fluid to a third pressure, which is
higher than the second pressure, for evaporating the working fluid
compressed to the third pressure, for relaxing the evaporated
working fluid to a pressure, which is lower than the third
pressure, so as to generate electrical current, and for liquefying
relaxed evaporated working fluid within the liquefier.
Inventors: |
Sedlak; Holger; (Sauerlach,
DE) ; Kniffler; Oliver; (Muenchen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Efficient Energy GmbH |
Sauerlach |
|
DE |
|
|
Family ID: |
39358078 |
Appl. No.: |
15/071534 |
Filed: |
March 16, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12526230 |
Feb 26, 2010 |
9316422 |
|
|
15071534 |
|
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Current U.S.
Class: |
60/641.2 ;
60/670; 62/238.7 |
Current CPC
Class: |
F24T 10/30 20180501;
Y02E 10/46 20130101; F24T 10/10 20180501; F25B 30/06 20130101; F24T
2010/56 20180501; F01K 7/16 20130101; Y02E 10/10 20130101; F25B
9/002 20130101; F05D 2220/31 20130101; F01D 15/10 20130101; F25B
30/00 20130101 |
International
Class: |
F25B 30/06 20060101
F25B030/06; F01D 15/10 20060101 F01D015/10; F24J 3/08 20060101
F24J003/08; F01K 7/16 20060101 F01K007/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2007 |
DE |
102007005930.4 |
Feb 4, 2008 |
EP |
PCT/EP2008/000875 |
Claims
1. A heat pump comprising: a first portion configured for
evaporating a working fluid at a first pressure, configured for
compressing the evaporated working fluid to a second, higher
pressure, and configured for liquefying the compressed working
fluid within a liquefier; and a second portion configured for
compressing liquid working fluid to a third pressure, which is
higher than the second pressure, configured for evaporating the
working fluid compressed to the third pressure, configured for
relaxing the evaporated working fluid so as to generate electrical
current, and configured for liquefying relaxed evaporated working
fluid within the liquefier.
2. The heat pump as claimed in claim 1, wherein the first portion
is configured to employ, for compressing the evaporated working
fluid, electrical current coming from the second portion or from an
external power supply network, and wherein the second portion is
configured to at least partly feed the electrical current into the
external power supply network.
3. The heat pump as claimed in claim 1, wherein the working fluid
is water.
4. The heat pump as claimed in claim 1, wherein the first portion
is configured to generate an evaporator at a first pressure smaller
than 20 hPa, and to generate a compression to a second pressure
which is more than 5 hPa higher than the first pressure.
5. The heat pump as claimed in claim 1, wherein the second portion
is configured to compress to a third pressure higher than 0.2
MPa.
6. The heat pump as claimed in claim 1, wherein the second portion
is configured to compress liquefied working fluid, which originates
from the liquefier, to the third pressure.
7. The heat pump as claimed in claim 1, wherein the second portion
is configured to evaporate the liquid working fluid, which has been
compressed to the third pressure, while using a primary energy
source, the primary energy source comprising a waste gas stream of
a combustion process of a heat dissipator of a solar collector.
8. The heat pump as claimed in claim 1, wherein the liquefier
comprises two supply lines, a first supply line being connected to
a dynamic compressor of the first portion, and the second supply
line being connected to a turbine of the second portion.
9. The heat pump as claimed in claim 1, wherein a coupler having an
input side and an output side is provided, wherein the coupler
comprises, on the input side, two supply lines, a first supply line
being connected to a dynamic-type compressor of the first portion,
and a second supply line being connected to the turbine of the
second portion, and wherein the coupler is connected, on the output
side, to the liquefier, the coupler being configured to couple
either the first supply line or the second supply line or both
supply lines to the liquefier at the same time.
10. The heat pump as claimed in claim 1, comprising a controller so
as to couple, in response to a control signal, an output for
electrical current of the turbine of the second portion to an input
for electrical energy of a dynamic compressor of the first
portion.
11. The heat pump as claimed in claim 1, wherein the second portion
comprises a liquid pump, an evaporator which may be coupled to a
heat source, a turbine for providing electrical current, and the
liquefier, the heat source being dimensioned such that the working
fluid evaporates at the third pressure.
12. The heat pump as claimed in claim 1, wherein the second portion
is configured to evaporate the liquid working fluid, which has been
compressed to the third pressure, while using a primary energy
source, the primary energy source comprising at least one of a
waste gas stream of a wood-fired oven within a building or a waste
gas stream of a pellet oven within the building and a heat
dissipator of a solar collector on the building, wherein the
liquefier comprises a heating advance flow for feeding heating
liquid to a heating system of the building and a heating backflow
for feeding the heating liquid back from the heating system into
the liquefier, wherein the first portion is configured to employ,
for compressing the evaporated working fluid, electrical current
coming from the second portion or from an external power supply
network, and wherein the second portion is configured to at least
partly feed the electrical current into the external power supply
network.
13. The heat pump as claimed in claim 12, wherein the first portion
is configured to generate an evaporation at a first pressure
smaller than 20 hPa, and to generate a compression to a second
pressure which is more than 5 hPa higher than the first pressure,
and wherein the second portion is configured to compress to a third
pressure higher than 0.2 MPa, wherein the working fluid is water,
wherein the evaporated working fluid is water steam, wherein the
compressed evaporated working fluid is compressed water steam, and
wherein the liquid working fluid is water.
14. The heat pump of claim 1, wherein the liquefier comprises a
heat exchanger, the heat exchanger being configured to be fed with
the advance flow and comprising the backflow, the heat exchanger
cooling water present within the liquefier, and heating up a
separate heating liquid for the heating system of the building.
15. The heat pump of claim 1, wherein the heating system is a floor
heating system.
16. The heat pump of claim 1, wherein the heating and the heating
backflow are configured to directly feed the working liquid into
the heating system of the building so that the liquid working fluid
and the heating liquid are identical.
17. A method of pumping heat, comprising: operating a first
portion, operating the first portion comprising evaporating a
working fluid at a first pressure, compressing the evaporated
working fluid to a second, higher pressure, and liquefying a
compressed working fluid within a liquefier; or operating a second
portion, the operation of the second portion comprising compressing
liquid working fluid to a third pressure, which is higher than the
second pressure, evaporating the working fluid which has been
compressed to the third pressure, relaxing the evaporated working
fluid to a pressure smaller than the third pressure, so as to
generate electrical current, and liquefying relaxed evaporated
working fluid within the evaporator.
18. A small power station for heating buildings, comprising: a
water pump for compressing water to a first pressure above 0.1 MPa;
an evaporator for evaporating the compressed water using primary
energy from a combustion process or from a solar collector so as to
provide water vapor at the first pressure; a turbine for generating
electrical current, the turbine being configured to bring water
vapor up to a second pressure while outputting electrical current,
the second pressure being smaller than 50 kPa; and a liquefier for
liquefying the cooled-off water vapor, the liquefier comprising a
heating advance flow and a heating backflow for heating a
building.
19. A method of heating a building, comprising: compressing water
to a first pressure above 0.1 MPa; evaporating the compressed water
while using primary energy from a combustion process or from a
solar collector, so as to provide water vapor at the first
pressure; generating electrical current by relaxing the water vapor
at the first pressure to a second pressure, the second pressure
being smaller than 50 kPa; and liquefying the water vapor, which
has been output by generating electrical current, within a
liquefier water volume coupled to a heating advance flow and a
heating backflow for heating a building.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. patent
application Ser. No. 12/526,230 filed Feb. 26, 2010, which is a
U.S. national entry of PCT Patent Application Serial No.
PCT/EP2008/000875 filed 4 Feb. 2008, and claims priority to German
Patent Application No. 102007005930.4 filed 6 Feb. 2007, which are
incorporated herein by references in their entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a heat pump and, in
particular, to a heat pump comprising a power generation
property.
[0003] FIG. 8 shows a known heat pump as is described in
"Technische Thermodynamik", Theoretische Grundlagen and praktische
Anwendungen, 14th revised edition, Hanser Verlag, 2005, pp.
278-279. The heat pump includes a closed cycle, within which a
working substance, such as R134a, circulates. Via a first heat
exchanger 80 and the evaporator, so much heat is withdrawn from the
soil, or the ground water, that the working substance evaporates.
The working substance, which now is rich in energy, is extracted by
the compressor via the suction line. Within the compressor 81, it
is compressed, thus increasing pressure and temperature. This
compression is performed by a piston compressor. The working
substance, which has been compressed and exhibits a high
temperature, now passes into the second heat exchanger 82, the
liquefier. Within the liquefier, so much heat is withdrawn from the
working substance by the heating or process-water cycle that the
coolant, being subject to high pressure and high temperature, is
liquefied. Within the choke or expansion member 83, the working
substance is expanded, i.e. the working substance is relieved of
stress. Here, pressure and temperature are reduced to such an
extent that the working substance is again able to re-absorb energy
from the soil or the ground water within the evaporator. Now the
cycle is complete and starts again.
[0004] As can be seen from this, the working substance serves as an
energy transporter so as to take up heat from the soil or ground
water, and to give it off, within the liquefier, to the heating
cycle. In this process management, the 2nd law of thermodynamics is
complied with, said law stating that heat or energy only be
transferred, "on its own", can from a higher temperature level to a
lower temperature level, and that inversely this may also occur by
means of energy supply from outside, here by the driving work of
the compressor.
[0005] FIG. 7 shows a typical h, log p diagram (h is the enthalpy,
p the pressure of a material). An isobaric evaporation of the
working substance takes place, between point 4 and point 1 in the
diagram of FIG. 7, at low values for the pressure and the
temperature (p1, T1). Here, the heat Q81 is supplied.
[0006] Ideally, a reversible compression of the working substance
vapor to a pressure of p2 is performed, between point 1 and point
2, within an adiabatic compressor. The temperature rises to T2 in
the process. A work of compression is to be supplied here.
[0007] Then, isobaric cooling of the working substance vapor from 2
to 2' is performed at a high pressure p2. Overheating is reduced.
Subsequently, the working substance is liquefied. Overall, the heat
Q25 can be dissipated.
[0008] Within choke 83, the working substance is choked, in an
adiabatic manner, from the high pressure p2 to the low pressure p1.
In the process, part of the liquid working substance evaporates,
and the temperature falls to the evaporating temperature T1. In the
h, log p diagram, the energies and characteristics of this process
may be calculated by means of enthalpies, and may be illustrated,
as is shown in FIG. 7.
[0009] The working fluid of the heat pump thus takes up, within the
evaporator, heat from the surroundings, i.e. air, water, waste
water or the soil. The liquefier serves as a heat exchanger for
heating up a heating substance. Temperature T1 is slightly lower
than the ambient temperature, temperature T2 is considerably higher
and temperature T2' slightly higher than the heating temperature
involved. The higher the temperature difference called for, the
more work may be effected by the compressor. Therefore, it is
desired to keep the rise in temperature as small as possible.
[0010] Thus, with regard to FIG. 7, a compression of the working
material vapors is performed, in the ideal case, along the curve
for the entropy s=constant up to point 2. From here up to point 3,
the working material liquefies. The length of the distance 2-3
represents the useful heat Q. From point 3 to point 4, the working
material is expanded, and from point 4 to point 1, it is
evaporated, the distance 4-1 reflecting the heat withdrawn from the
heat source. Unlike the T, s diagram, the magnitudes of the heat
and of the work may be taken as distances in the h, log p diagram.
Pressure losses within valves, within the pressure and suction
lines, of the compressor, etc. change the ideal curve of the cyclic
process in the h, log p diagram and reduce the effectiveness of the
entire process.
[0011] With piston compressors, the working material vapor which
has been sucked in initially has a lower temperature than the
cylinder wall of the compressor, and thus absorbs heat from it. As
the compression increases, the temperature of the working material
vapor eventually increases to exceed that of the cylinder wall, so
that the working material vapor gives off heat to the cylinder
wall. Then, when the piston again sucks in and compresses vapor,
the temperature of the piston wall is initially fallen below again
and then exceeded, which leads to constant losses. In addition,
overheating of the working material vapor which has been sucked in
will be called for and useful for the compressor to no longer suck
in any liquid working material. What is also disadvantageous, in
particular, is the heat exchange with the oil cycle of the piston
compressor, which is indispensable for lubrication.
[0012] Any irreversible processes, such as heat losses during
compression, pressure losses within the valves, and flow losses
within the pressure line for liquefying and within the liquefier,
will increase the entropy, i.e. the heat which cannot be retrieved.
In addition, temperature T2, also exceeds the liquefying
temperature. Such an "overheating enthalpy" is undesired, in
particular because the high temperatures occurring in the process
will accelerate the aging of the compressor and, in particular, of
the lubricating oil within a piston compressor. Also, the
effectiveness of the process is reduced.
[0013] The liquefied working material at a low temperature at the
output of the liquefier would have to be expanded, within the
context of an ideal cyclic process, via an engine, for example a
turbine, so as to exploit the excess energy which was present in
comparison with the state present at the temperature and the
pressure prior to compressing. Because of the great expenditure
involved for this, this measure is dispensed with, and the pressure
of the working material is abruptly reduced to the low pressure and
the low temperature by the choke 83. The enthalpy of the working
material remains approximately the same in the process. Due to the
abrupt pressure reduction, the working material may partially
evaporate to reduce its temperature. The evaporation heat that may
be used is derived from the working material exhibiting excess
temperature, i.e. is not withdrawn from the heat source. The
entirety of the losses caused by the expansion within choke 83
(FIG. 8) is referred to as expansion losses. These are exergy
losses because heat of a temperature T is converted to heat of a
temperature T0. These losses may be reduced if the liquid working
material can dissipate its heat to a medium having a temperature
smaller than T. This undercooling enthalpy may be exploited by an
internal heat exchange which, however, also involves additional
expenditure in terms of equipment. Also in principle, the internal
heat exchange has its limitation, because in the compression of the
vapors, the overheating temperature T2 increases, whereby the gains
achieved are partly cancelled out, and because also more thermal
strain is put on the machine and the lubricating oil. Eventually,
the overheating causes the volume of the vapor to increase, whereby
the volumetric heat power decreases. This heat is utilized for
preheating those vapors of the working material which flow to the
compressor, only to the extent useful in order to be sure that all
droplets contained in the vapor of the working medium are converted
to vapor.
[0014] In general, one may state that the ratio of the enthalpy
difference between point 1 and point 4 and the enthalpy difference
between point 2 and point 1 of the h, log p diagram is a measure of
the economic efficiency of the heat pump process.
[0015] A working substance which is currently popular is R134a, the
chemical formula of which is CF3-CH2F. It is a working substance
which, even though it is no longer damaging to the ozone layer,
nevertheless has an impact, in terms of the greenhouse effect,
which is 1000 times higher than that of carbon dioxide. However,
the working substance R134a is popular since it has a relatively
large enthalpy difference of about 150 kJ/kg.
[0016] Even though this working substance is no longer an "ozone
killer", there are nevertheless considerable requirements placed
upon the completeness of the heat pump cycle, to the effect that no
molecules of the working substance will escape from this closed
cycle, since they would cause considerable damage due to the
greenhouse effect. This encapsulation leads to considerable
additional cost when building a heat pump.
[0017] Also, one may assume that by the time the next stage of the
Kyoto Protocol is implemented, R134a will be prohibited by the year
2015 because of the greenhouse effect, which has also happened to
previous, considerably more damaging substances.
[0018] What is therefore disadvantageous about existing heat pumps,
beside the fact of the harmful working substance, is also the fact
that, due to the many losses within the heat pump cycle, the
efficiency factor of the heat pump typically does not exceed a
factor of 3. In other words, 2 times the energy that has been used
for the compressor may be withdrawn from the heat source, such as
the ground water or the soil. When considering heat pumps wherein
the compressor is driven by electrical current, and when
considering, at the same time, that the efficiency factor in
current generation is perhaps 40%, one will find that--with regard
to the overall energy balance--the use of a heat pump is very
questionable. In relation to the source of primary energy,
120%=340% of heat energy are provided. A conventional heating
system using a burner achieves efficiency factors of at least
90-95%, i.e. an improvement of only 25-30% is achieved at high
technical and, therefore, financial expense.
[0019] Improved systems use primary energy for driving the
compressor. Thus, gas or oil is burned to provide the compressor
rating using the energy released by combustion. What is
advantageous about this solution is the fact that the energy
balance actually becomes more positive. The reason for this is that
even though only about 30% of the source of primary energy may be
used as driving energy, the waste heat of, in this case, about 70%
can also be used for heating. The heating energy provided will then
amount to 160%=330%+70% of the source of primary energy. What is
disadvantageous about this solution, however, is that a household
may nevertheless use a combustion engine and a fuel store even
though it has no longer a classical heating system. The expenditure
made for engine and fuel storage may be added to the expense made
for the heat pump, which, after all, is a highly closed cycle due
to the coolant being harmful to the climate.
[0020] All of these things have resulted in that heat pumps have
had only limited success in competition with other types of heating
systems.
[0021] Consequently, a heat pump is characterized in that
mechanical energy is input into a system, and thermal energy at a
higher temperature level is output. The outcome of the heat pump is
positive when the energy output at the high temperature level is at
least higher than the electrical energy employed for compression.
In this context, it may obviously be taken into account that--when
one assumes primary energy consumption as the basis--the electrical
energy also has been generated only at a limited efficiency factor,
for example by means of a combustion process.
[0022] On the other hand, thermal energy is withdrawn from the heat
source by the evaporating refrigerant in a closed cycle in
refrigerating plants, said thermal energy is pumped, by using
mechanical energy, to a higher temperature level by means of a
compressor and is finally condensed again so as to dissipate the
thermal energy to the heat sink in addition to the mechanical
energy. This, too, is referred to as a heat pump. Typically, the
pressure employed is overpressure in relation to atmospheric
pressure.
[0023] Also in large-scale plants such as nuclear power stations,
for example, water is evaporated in that primary energy is
converted to heat which evaporates water, as a result of which
steam turbines are driven, which in turn drive a generator. The
water vapor is condensed in enormous cooling towers to retrieve the
water. Electrical or mechanical energy and waste heat are formed in
the process. In addition to political problems, an essential
disadvantage of such a power station are also the enormous
manufacturing costs and the decentralized operation associated
therewith.
[0024] DE OS 2745127 discloses a method of driving a heat pump or
refrigerating machine wherein a mass flux is heated up within a
heat exchanger and is supplied to an expansion machine as liquid or
saturated steam. The expansion machines drives a compression
machine which compresses a steam drawn in by an evaporator. The
compressed steam is fed to a capacitor. The expansion machine and
the compression machine are mechanically coupled.
SUMMARY
[0025] According to an embodiment, a heat pump may have: a first
portion for evaporating a working fluid at a first pressure, for
compressing the evaporated working fluid to a second, higher
pressure, and for liquefying the compressed working fluid within a
liquefier; and a second portion for compressing liquid working
fluid to a third pressure, which is higher than the second
pressure, for evaporating the working fluid compressed to the third
pressure, for relaxing the evaporated working fluid so as to
generate electrical current, and for liquefying relaxed evaporated
working fluid within the liquefier.
[0026] According to another embodiment, a method of pumping heat
may have the steps of: operating a first portion, operating the
first portion including evaporating a working fluid at a first
pressure, compressing the evaporated working fluid to a second,
higher pressure, and liquefying a compressed working fluid within a
liquefier; or operating a second portion, the operation of the
second portion including compressing liquid working fluid to a
third pressure, which is higher than the second pressure,
evaporating the working fluid which has been compressed to the
third pressure, relaxing the evaporated working fluid to a pressure
smaller than the third pressure, so as to generate electrical
current, and liquefying relaxed evaporated working fluid within the
evaporator.
[0027] According to another embodiment, a small power station for
heating buildings may have: a water pump for compressing water to a
first pressure above 0.1 MPa; an evaporator for evaporating the
compressed water using primary energy from a combustion process or
from a solar collector so as to provide water vapor at the first
pressure; a turbine for generating electrical current, the turbine
being configured to bring water vapor up to a second pressure while
outputting electrical current, the second pressure being smaller
than 50 kPa; and a liquefier for liquefying the cooled-off water
vapor, the liquefier including a heating advance flow and a heating
backflow for heating a building.
[0028] According to another embodiment, a method of heating a
building may have the steps of: compressing water to a first
pressure above 0.1 MPa; evaporating the compressed water while
using primary energy from a combustion process or from a solar
collector, so as to provide water vapor at the first pressure;
generating electrical current by relaxing the water vapor at the
first pressure to a second pressure, the second pressure being
smaller than 50 kPa; and liquefying the water vapor, which has been
output by generating electrical current, within a liquefier water
volume coupled to a heating advance flow and a heating backflow for
heating a building.
[0029] The present invention is based on the finding that a heat
pump having a first portion, by means of which thermal energy at a
relatively high temperature level is obtained by compressing steam
using mechanical energy, may be ideally combined with a second
portion, wherein a liquid working fluid is compressed, and wherein
the liquid working fluid, which is subject to a relatively high
pressure, is evaporated using an external source of energy. The
steam which is highly pressurized is then relaxed via a turbine,
which results in electrical energy; then the steam leaving the
turbine--which is at a low pressure and a comparatively low
temperature--is fed to the same liquefier which acts as a liquefier
also in the first portion of the heat pump. Thus, the inventive
heat pump comprises three different pressure zones. The first
pressure zone is the zone having the lowest pressure, wherein the
working fluid is evaporated at a low pressure and, thus, at a low
temperature. In an advantageous embodiment of the invention, the
pressure of this low pressure zone exhibits values of less than 20
hPa.
[0030] Compression of the steam leads to compressed water vapor,
which has a second, higher pressure. Due to the compression of the
steam, the temperature of the steam rises to the higher temperature
level; due to the liquefaction of the compressed steam, heat may be
extracted from the steam and may be used for heating buildings, for
example. The second pressure is at least 5 hPa higher than the
first pressure, and typically is even about double the first
pressure.
[0031] Unlike the first portion, no steam, but a liquid working
fluid is compressed in the second portion of the heat pump; to
achieve this, relatively low-cost devices are sufficient in
contrast to the compression of steam, namely typically water pumps
having a power consumption of a few Watt. The third pressure
exhibited by the pressurized water amounts to 0.5 to 3 MPa, which
corresponds to evaporation temperatures of about 120 to 235 degrees
Celsius in the case of water.
[0032] While external energy is supplied, the pressurized water is
evaporated, said external energy being a waste gas stream of a
burner, or a heat dissipation of a solar collector. The hot steam,
which is highly pressurized and which is particularly high
especially in comparison with the area of low pressure, which
exhibited by the liquefier, namely is higher by a factor of 500,
for example, is relaxed down to the low-pressure area via a
turbine, wherein there is also a low temperature, which area also
exhibits a temperature in the order of magnitude of from 30 to 40
degrees, which may readily be used for feeding an underfloor
heating system.
[0033] In accordance with the present invention, therefore, in the
second portion of the heat pump the externally provided energy is
used, on the one hand, for generating electrical current which may
either be fed into the power supply network or which may drive the
compressor of the first heat pump portion, or which is at least
partly fed into the power supply network and may partly drive the
compressor, and additionally, thermal energy is obtained within the
liquefier, said thermal energy being readily usable for heating
buildings. What is advantageous is in particular that a working
fluid steam is present at the output of the turbine, said steam
being relatively similar, in terms of its temperature and pressure
properties, to the working fluid steam which is generated by means
of compression from the pressure area exhibiting the first low
pressure.
[0034] Thus, in accordance with the invention, energy is extracted
from a heat source by means of evaporation, it being possible for
this heat pump to be a solar collector, a wood-fired oven, a pellet
oven or any other burner. This energy is partly converted to
mechanical energy, the remainder being supplied to a heat sink
during liquefaction. This heat sink is identical with a typical
heat sink of a heat pump based on vapor compression, as is
favorable for heating buildings, for example.
[0035] Advantageously, water is used as the working liquid or
refrigerant, a low-pressure area already being present due to the
first portion of the heat pump, said low-pressure area ensuring
that a high pressure difference is obtained, namely between the
high pressure exhibited by the vapor which is generated due to the
external heat supply, and the low pressure existing within the
liquefier. This low-pressure area enables the process employed to
be utilized on a smaller scale, namely for heating buildings, and
thus to be employed in a decentral manner and with all of the
advantages.
[0036] In addition, it is advantageous to switch in the first
portion of the heat pump and to triple the heating energy which may
thus be achieved and which is contained within a primary energy
source. This is achieved in that the energy released by the
combustion is not directly used for heating water, but is employed
to evaporate the highly pressurized water, which results in that,
due to the relaxation to the second-pressure area, electrical
current is generated which is then at least partly used for
compressing the vapor employed in the first heat pump portion.
[0037] In advantageous embodiments, water is used in the first and
second portions. In comparison with the working substance R134a,
which is frequently used these days, water additionally has a
considerably larger ratio of the enthalpy differences. The enthalpy
difference, which is decisive in terms of how effective the heat
pump process is, amounts to about 2500 kJ/kg for water, which is
about 16 times as much as the usable enthalpy difference of R134a.
The compressor enthalpy to be expended, by contrast, is only 4-6
times as large, depending on the operating point.
[0038] In addition, water is not harmful to the climate, i.e. is
neither an ozone killer, not does it aggravate the greenhouse
effect. This enables heat pumps to be built in a considerably
simpler manner, since the requirements placed upon the completeness
of the cycle are not high. Instead, it is even advantageous to
completely leave behind the closed process and to make an open
process instead, wherein the ground water, or the water
representing the exterior heat source, is directly evaporated.
[0039] Advantageously, the evaporator is configured such that it
comprises an evaporation chamber within which the evaporation
pressure is lower than 20 hPa (hectopascal), so that water will
evaporate at temperatures below 18.degree. C. and, advantageously,
below 15.degree. C. In the northern hemisphere, typical ground
water has temperatures of between 8 and 12.degree. C., which
involves pressures of below 20 hPa for the ground water to
evaporate, so as to be able to achieve, by evaporating the ground
water, a reduction in the temperature of the ground water and,
thus, heat removal, by means of which a heating system within a
building, such as a floor heating system, may be operated.
[0040] In addition, water is advantageous in that water vapor takes
up a very large volume, and in that one need no longer fall back on
a displacement machine such as a piston pump or the like in order
to compress the water vapor, but that a high-performance compressor
in the form of a dynamic-type compressor, such as a radial-flow
compressor, may be employed which is highly controllable in terms
of its technology and is cost-efficient in terms of its production
since it exists in high quantities and has been used up to now as a
small turbine or as a turbocompressor in cars, for example.
[0041] A prominent representative of the pedigree of dynamic-type
compressors as compared to displacement machines is the radial-flow
compressor, for example in the form of a turbocompressor comprising
a radial-flow wheel.
[0042] The radial-flow compressor, or the dynamic-type compressor,
may achieve at least such a level of compression that the output
pressure exiting from the radial-flow compressor is at least 5 hPa
higher than the input pressure into the radial-flow compressor.
Advantageously, however, a compression will have a ratio larger
than 1:2, and even larger than 1:3.
[0043] Compared to piston compressors, which are typically employed
within closed cycles, dynamic-type compressors additionally have
the advantage that the compressor losses are highly reduced, due to
the temperature gradient existing within the dynamic-type
compressor, as compared with a displacement machine (piston
compressor), wherein such a stationary temperature gradient does
not exist. What is particularly advantageous is that an oil cycle
is completely dispensed with.
[0044] Moreover, multi-stage dynamic-type compressors may be
particularly used to achieve the relatively high level of
compression which should have a factor of 8 to 10 in order to
achieve sufficient advance flow temperature in a heating system
even for cold winter days.
[0045] In an advantageous embodiment, a fully open cycle is
employed, wherein the ground water is made to have the low
pressure. An advantageous embodiment for generating a pressure
below 20 hPa for ground water consists in the simple use of a riser
pipe leading to a pressure-tight evaporation chamber. If the riser
pipe overcomes a height of between 9 and 10 m, the evaporation
chamber will comprise the low pressure that may be used at which
the ground water will evaporate at a temperature of between 7 and
12.degree. C. Since typical buildings are at least 6 to 8 m in
height and since in many regions, the ground water is present
already at 2 to 4 m below the surface of the earth, installing such
a pipe leads to no considerable additional expense since one may
only dig a little deeper than for the foundations of the house, and
since typical heights of buildings are readily high enough for the
riser pipe or the evaporation chamber not to protrude above the
building.
[0046] For cases of application wherein only a shorter riser pipe
is possible, the length of the riser pipe may be readily reduced by
a pump/turbine combination which only involves a minor amount of
additional work from the outside due to the fact that the turbine
is used for converting the high pressure to the low pressure, and
the pump is used for converting the low pressure to the high
pressure.
[0047] Thus, primary heat-exchanger losses are eliminated, since no
primary heat exchanger is used but use is made of the evaporated
ground water directly as a working vapor or a working
substance.
[0048] In an advantageous embodiment, no heat exchanger is used
even in the liquefier. Instead, the water vapor which is heated up
due to being compressed is directly fed into the heating-system
water within a liquefier, so that within the water, a liquefaction
of the water vapor takes place such that even secondary
heat-exchanger losses are eliminated.
[0049] The advantageously utilized water evaporator/dynamic-type
compressor/liquefier combination thus enables efficiency factors of
at least 6 in comparison with common heat pumps. Thus, it is
possible to withdraw from the ground water at least 5 times the
amount of the electric energy spent for compression, so that a
heating energy of 240%=640%, in relation to the source of primary
energy, is provided even if the dynamic-type compressor is operated
with electrical current. As compared with the prior art, this
represents at least double the efficiency or half of the energy
costs. This is particularly true for the emission of carbon
dioxide, which is relevant in terms of the climate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] Embodiments of the present invention will be detailed
subsequently referring to the appended drawings, in which:
[0051] FIG. 1a is a basic block diagram of the inventive heat
pump;
[0052] FIG. 1b is a table for illustrating various pressures and
the evaporation temperatures associated with these pressures;
[0053] FIG. 1c is a schematic overview of a small power
station;
[0054] FIG. 1d is a schematic overview of the heat pump having the
first portion and the second portion in accordance with an
embodiment;
[0055] FIG. 2 is a block diagram of an advantageous embodiment of
the inventive heat pump having the first portion which is operated
with ground water, sea water, etc, and having the second portion
which may be employed for power generation;
[0056] FIG. 3a is an alternative embodiment of the liquefier of
FIG. 2;
[0057] FIG. 3b is an alternative embodiment of the liquefier with a
reduced backflow in the off operation;
[0058] FIG. 3c is a schematic representation of the liquefier
having a gas separator;
[0059] FIG. 4a is an advantageous implementation of the evaporator
of FIG. 2;
[0060] FIG. 4b is an alternative embodiment of the evaporator using
the liquefier drain as a boiling assistance;
[0061] FIG. 4c is an alternative embodiment of the evaporator
having a heat exchanger for using ground water for boiling
assistance;
[0062] FIG. 4d is an alternative embodiment of the evaporator
comprising feeding from the side and draining in the center;
[0063] FIG. 4e is a schematic representation of the expander with
an indication of advantageous measurements;
[0064] FIG. 5a is an alternative implementation of the evaporator
for reducing the height of the riser pipe;
[0065] FIG. 5b is an implementation of an alternative realization
of connecting a heating line to the liquefier with a turbine/pump
combination;
[0066] FIG. 6a is a schematic representation of the compressor
performed by several dynamic-type compressors arranged one behind
the other;
[0067] FIG. 6b is a schematic representation of the setting of the
numbers of revolutions of two cascaded dynamic-type compressors as
a function of the target temperature;
[0068] FIG. 6c is a schematic top view of a radial-flow wheel of a
dynamic-type compressor in accordance with an advantageous
embodiment of the present invention;
[0069] FIG. 6d is a schematic cross-sectional view with a merely
schematical representation of the radial-wheel vanes for
illustrating the different expansions of the vanes with regard to
the radius of the radial-flow wheel;
[0070] FIG. 7 is an exemplary h, log p diagram; and
[0071] FIG. 8 is a known heat pump performing the left-handed cycle
of FIG. 7.
DETAILED DESCRIPTION OF THE INVENTION
[0072] Before providing a more detailed explanation of the subject
matter of the present invention with reference to FIGS. 1c and 1d
and FIG. 2, the first portion of an inventive heat pump shall be
presented with reference to FIGS. 1a and 1b.
[0073] FIG. 1a shows an inventive heat pump which initially
comprises a water evaporator 10 for evaporating water as a working
fluid so as to generate, on the output side, a vapor within a
working vapor line 12. The evaporator includes an evaporation
chamber (not shown in FIG. 1a) and is configured to generate,
within the evaporation chamber, an evaporation pressure lower than
20 hPa, so that the water will evaporate within the evaporation
chamber at temperatures below 15.degree. C. The water is
advantageously ground water, brine circulating freely within the
soil or within collector pipes, i.e. water with a specific salt
content, river water, lake water or sea water. In accordance with
the invention, all types of water, i.e. limy water, non-limy water,
saline water or non-saline water, are advantageously used. This is
due to the fact that all types of water, i.e. all of these "water
materials", have the favorable property of water, i.e. consisting
in that water, also known as "R718", has an enthalpy-difference
ratio of 6 usable for the heat pump process, which corresponds to
more than double a typically usable enthalpy-difference ratio of,
e.g., R134a.
[0074] The water vapor is fed, by suction line 12, to a
compressor/liquefier system 14 comprising a dynamic-type
compressor, such as a radial-flow compressor, for example in the
form of a turbocompressor designated by 16 in FIG. 1a. The
dynamic-type compressor is configured to compress the working vapor
to a vapor pressure of at least more than 25 hPa. 25 hPa correspond
to a liquefying temperature of about 22.degree. C., which may
already be a sufficient heating-system advance flow temperature of
a floor heating system, at least on relatively warm days. In order
to generate higher advance flow temperatures, pressures of more
than 30 hPa may be generated using dynamic-type compressor 16, a
pressure of 30 hPa having a liquefying temperature of 24.degree.
C., a pressure of 60 hPa having a liquefying temperature of
36.degree. C., and a pressure of 100 hPa corresponding to a
liquefying temperature of 45.degree. C. Floor heating systems are
designed to be able to provide sufficient heating with an advance
flow temperature of 45.degree. C. even on very cold days.
[0075] The dynamic-type compressor is coupled to a liquefier 18
which is configured to liquefy the compressed working vapor. By the
liquefaction, the energy contained within the working vapor is fed
to the liquefier 18 so as to be fed to a heating system via the
advance flow 20a. Via backflow 20b, the working fluid flows back
into the liquefier.
[0076] In accordance with the invention, it is advantageous to
extract the heat (heat energy) from the high-energy water vapor
directly by the colder heating water, said heat (heat energy) being
taken up by the heating-system water so that the latter heats up.
In the process, so much energy is extracted from the vapor that
same becomes liquefied and also participates in the heating
cycle.
[0077] Thus, a loading of material into the liquefier, or the
heating system, takes place, the loading being regulated by a drain
22, such that the liquefier in its liquefaction chamber has a water
level which remains below a maximum level despite the constant
supply of water vapor and, thereby, of condensate.
[0078] As has already been explained, it is advantageous to take an
open cycle, i.e. to evaporate the water, which represents the heat
source, directly without a heat exchanger. Alternatively, however,
the water to be evaporated could also initially be heated up by an
external heat source via a heat exchanger. However, what is to be
taken into account in this context is that this heat exchanger
again signifies losses and expenditure in terms of apparatus.
[0079] In addition, it is advantageous, in order to avoid losses
for the second heat exchanger which has been present so far on the
liquefier side, to use the medium directly even there, i.e. to let
the water, which comes from the evaporator, circulate directly
within the floor heating system, when considering a house
comprising a floor heating system.
[0080] Alternatively, however, a heat exchanger may be arranged, on
the liquefier side, which is fed with the advance flow 20a and
which comprises the backflow 20b, this heat exchanger cooling the
water present within the liquefier, and thus heating up a separate
floor heating liquid which will typically be water.
[0081] Due to the fact that the working medium used is water, and
due to the fact that only the evaporated portion of the ground
water is fed into the dynamic-type compressor, the degree of purity
of the water is irrelevant. Just like the liquefier and, as the
situation may be, the directly coupled floor heating system, the
dynamic-type compressor is provided with distilled water such that,
in comparison with present-day systems, the system has a reduced
maintenance expenditure. In other words, the system is
self-cleaning, since the system is only ever fed with distilled
water, and since the water within the drain 22 is thus not
contaminated.
[0082] In addition, it shall be noted that dynamic-type compressors
have the properties that--similar to a turbine of an airplane--they
do not contact the compressed medium with problematic materials
such as oil. Instead, the water vapor is compressed only by the
turbine or the turbocompressor, but is not contacted with oil or
any other medium negatively affecting its purity, and thus is not
contaminated.
[0083] The distilled water dissipated through the drain may thus be
readily re-fed to the ground water--if no other regulations are in
the way. Alternatively, however, it may also be made to seep away,
e.g. in the garden or in an open area, or it may be fed to a waste
water purification plant via the sewage system, if the regulations
permit.
[0084] The inventive combination of water as a working substance
with the useful enthalpy-difference ratio which is doubly improved
as compared with R134a, and due to the consequently reduced
requirements placed upon the closed nature of the system (rather,
an open system is advantageous) and due to the use of the
dynamic-type compressor, by means of which the useful compression
factors are efficiently achieved without any negative effects on
the purity, an efficient heat pump process which is neutral in
terms of environmental damage is provided which will become even
more efficient if the water vapor is directly liquefied within the
liquefier, since, in this case, maybe not one single heat exchanger
might be used in the entire heat pump process.
[0085] In addition, any losses associated with the piston
compression are dispensed with. In addition, the losses, which are
very low in the case of water and which otherwise occur in the
choking, may be used to improve the evaporation process, since the
drain water having the drain temperature, which will typically be
higher than the ground water temperature, is advantageously used to
trigger a bubble evaporation within the evaporator by means of a
structuring 206 of a drain pipe 204, as will be explained in FIG.
4a, in order to increase the evaporation efficiency.
[0086] FIG. 1c shows the second portion of the inventive heat pump,
which may also be employed, however, as a small power station for
heating buildings without the first portion shown in FIG. 1a.
[0087] In particular, the second portion comprises the same
liquefier 18 represented by means of FIG. 1a and coupled to a
heating advance flow 20a and a heating backflow 20b. The drain 22
of the liquefier is no longer supplied to the channel or the
primary side, in accordance with the second portion of the
inventive heat pump, but is supplied to a water pump 1100 which
raises the water output by the liquefier 18 to a pressure of, e.g.,
2 MPa. This pressure of 2 MPa corresponds to 20 bar. Since the
water pump 1100 only achieves liquid compression, the temperature
of the water does not change by the activity of the water pump.
[0088] Since water or, generally, liquid working fluids may be
pressurized in a simple manner, the water pump that may be used
need only be a low-cost pump having a power consumption of a few
watts, such as 1 to 2 watts.
[0089] The pressurized water is supplied to a water evaporator
1102. The water evaporator 1102 obtains energy from a primary
heating, such as a burner for wood, wood pellets, oil, gas, etc.,
or from a solar collector, as is schematically depicted by an
energy feed line 1104. The high temperature that may be used for
evaporating the highly pressurized water may be readily generated
by means of a combustion process. Even modern solar collectors
readily provide temperatures higher than 150.degree. C., or even
around 200.degree. C., said temperatures already sufficing to
evaporate water which is held at a pressure of 16 bar, or has
pressurized to a level of 16 bar by the water pump 1100.
[0090] Therefore, highly pressurized, hot vapor is present at the
output of the water evaporator 1102, said vapor being optimally
suited to be relaxed via a turbine means, which is advantageously
configured as a stage turbine. The relaxation via the stage turbine
may be converted to electrical current while using corresponding
devices, for example using known generators, said electrical
current being output from the turbine 1106 via a power supply line
1108. Thus, an evaporated working fluid is present at the output of
the turbine/generator combination 1106, which will simply be
referred to as the "turbine" below, said evaporated working fluid
having the low second pressure and further having a temperature
which is suited to heat the working fluid present in a liquid form,
which is present in the liquefier, by means of condensation, or
liquefaction.
[0091] This thermal energy, which is emitted within the liquefier
18 by the vapor generated at the output of the turbine 1106, may
readily be used for reaching a heating system within a building,
namely via the heating advance flow 20a and/or the heating backflow
20b. The heating system within a building may operate without a
heat exchanger, which is possible when the working fluid is
directly supplied, in a liquid form, to a heating system, such as
radiators or underfloor heaters without the liquid cycle within the
radiators or underfloor heater being separated from the liquid
volume of the liquefier by a heat exchanger.
[0092] However, a heat exchanger may alternatively be provided,
which is useful when working fluids other than water are employed,
as will be explained with reference to FIG. 1d. However, for a
small power station for heating buildings, it is advantageous to
use water as the working liquid, and to have pressure ranges which
correspond to the evaporation temperatures of water at the
corresponding pressures.
[0093] An example referring to size is shown in FIG. 1c. The volume
flow rate of water is 4 ml per second, and it is assumed that the
liquefier drain has a temperature of 36.degree. C. The resulting
pressure within the liquefier is thus at 60 mbar or 60 hPa, as is
depicted in FIG. 1b. The water having a pressure of 60 mbar is
brought up to a pressure of 20 bar, or 2 MPa, by means of the water
pump 1100, which corresponds to a factor of 333. This pressure
difference is sufficiently large for using the inventive process to
drive a turbine 1106 to generate electrical current. Generally,
pressure differences larger than a factor 50 lead to an
advantageous yield of electrical energy, it also being possible for
the pressure differences to take on very high values if the water
pump 1100 is designed for this and if the energy supply via the
schematic energy feed line 1104 has a sufficiently high temperature
for the highly pressurized water to be evaporated, and for
generating, at the output of the water evaporator 1102, the vapor
which has a high temperature and a high pressure and is therefore
ideally suited to drive a turbine and thus to generate electrical
current 1108. In the example shown in FIG. 1c, the vapor has a
temperature of 215.degree. C. and a pressure of 2 MPa, or 20 bar.
The turbine 1106 is dimensioned such that it outputs a working
vapor having a temperature of 36.degree. C. and a pressure of 60
mbar. With the volume flow rate shown and the pressure and/or
temperature differences depicted, electrical current may be
generated in the order of magnitude of 1.5 kW. In addition, the
liquefier liquid volume is heated up by the condensed vapor at the
same time, so that, in addition to the current gain, advantageous
heating of buildings is also achieved.
[0094] In advantageous embodiments, the rate of the volume flow
through the system, i.e. the volume flow rate, of working fluid
within the line 22 ranges from 1 ml per second to 100 ml per
second. The second pressure, i.e. the pressure exhibited by the
vapor within the liquefier and exhibited by the water at the output
of the liquefier advantageously ranges from 25 hPa to 0.1 MPa, and
the pressure generated by the water pump advantageously is above
around 5 bar, and in particularly advantageous embodiments is in a
range above around 12 bar.
[0095] The temperature exhibited by the vapor at the output of the
water evaporator 1102 and/or at the output of the stage turbine
1106 results from the corresponding pressure of the vapor, as is
depicted in the table of FIG. 1b and as is also depicted in the
further table in FIG. 1d for larger pressures for some working
points.
[0096] In advantageous embodiments, the proper refrigerant is
combined with the proper working pressures. Water condenses as
early as at 22.degree. C. in an underpressure atmosphere of 26
mbar, or at 100.degree. C. at about 1.01 bar. By being condensed,
the water passes on its condensation energy to the heating-system
water, which is advantageously used directly for heating buildings.
The under-cooled water in the heating backflow is pressurized to
the high working pressure by the feed pump 1100. Within the water
evaporator, which advantageously comprises a heat exchanger, the
water evaporates and thus ensures a temperature which corresponds
to the pressure. At 100.degree. C., the pressure is 1 bar. At
200.degree. C., the pressure is 16 bar, and at 300.degree. C., the
pressure is 90 bar. The overpressure is used for driving the
turbine 1106 so as to convert the mechanical energy, which has been
absorbed due to the gas flow, to electrical energy, for example.
The vapor flows from the high-pressure side to the low-pressure
side, and the cycle starts again. If the condensation heat is not
sufficient for heating the building, it is advantageous to
additionally operate the first heat pump portion; for this purpose,
either the electrical current generated by the turbine 1106 is
used, or electrical current is obtained from the power supply
network. The latter case may be more favorable if the current
obtained from the power supply network is lower in cost than the
current output to the power supply network.
[0097] Thus, by burning a piece of wood, about three times the
amount of thermal energy may be provided for heating buildings than
if the wood had been used directly for heating the building. This
is due to the fact that the energy contained within the piece of
wood is employed to drive the first portion of the heat pump.
[0098] While FIG. 1c depicts an advantageous embodiment of the
small power station for heating buildings, FIG. 1d shows an
advantageous embodiment of the inventive heat pump comprising the
first portion and the second portion.
[0099] The first portion comprises the evaporator 10 for
evaporating a working fluid at the first (low) pressure. In
addition, the first portion comprises the dynamic-type compressor
16 for compressing the evaporated working fluid to a second, higher
pressure. Eventually, the first portion also comprises the
liquefier 18 for liquefying the compressed working fluid.
[0100] In accordance with the invention, the second portion is
further provided, by means of the water pump 1100, for compressing
a liquid working fluid to a third pressure, which is higher than
the second pressure. In addition, the second portion serves to
evaporate the working fluid, which has been compressed to the third
pressure, by means of the evaporator or heat exchanger 1102. In
addition, the second portion serves to relax the evaporated working
fluid, via a turbine 1106, to a pressure smaller than the third
pressure so as to generate the electrical current which may be
output via a line 1108. Moreover, the second portion also comprises
the liquefier 18 so as to liquefy the relaxed evaporated working
fluid within the liquefier 18.
[0101] The working fluid within the first and second portions of
the heat pump of FIG. 1d in accordance with the present invention
are identical if, as is shown in FIG. 1d, there is a working fluid
contact within the liquefier, i.e. if, as is shown in FIG. 1d, no
heat exchanger is employed with regard to the liquefier 18.
However, liquefaction may obviously also take place such that the
cycles of the working fluids within the second and first portions
are fluidically separated from each other, while, however, both
cycles within the liquefier are thermally coupled. However, it is
advantageous to employ one and the same working fluid and not only
a thermal, but also a fluidic coupling within the liquefier 18,
since in this case no heat exchangers might be used, but the output
line of the turbine 1106 may be directly coupled into the liquefier
or, via a simple coupler 1110, to the liquefier.
[0102] The coupler 1110 is configured to receive, on the input
side, both the output line of the dynamic-type compressor 16 of the
first portion and the output line of the turbine 1106 of the second
portion, while the output of the coupler 1110 is coupled to the
liquefier 18. Depending on the implementation, the coupler may
connect either the output of the dynamic-type compressor 16 or the
output of the turbine 1106 to the output, or the coupler may
connect both outputs to the liquefier 18 in parallel, depending on
the requirement and implementation of the dynamic-type
compressor.
[0103] In addition, the liquefier 18 is coupled to the water
evaporator 10 via a switch 1114, which may be configured to
represent a normal drain when the second portion of the heat pump
is deactivated.
[0104] Alternatively, when the second portion is deactivated, the
drain water 22 may be directly fed into the primary-side evaporator
cycle, as is shown in FIG. 2.
[0105] The switch 1140 may further be implemented to provide both
the water pump 1100 and the water evaporator 10 with liquid. This
is due to the fact that the advantageous implementation of the
first portion represents an open cycle, since working fluid is
taken from the environment, for example from ground water, and is
recycled back to the environment somewhere else, whereas the cycle
occurring in the second portion is a closed cycle, since liquefier
water may again and again be compressed, evaporated, relaxed and
liquefied. Alternatively, however, both the first cycle and the
second cycle within the first portion and the second portion,
respectively, may be configured as open cycles. This is possible
when the working fluid is water, i.e. when no contamination takes
place, as is not the case, in particular, when a radial-flow wheel
is employed as the dynamic-type compressor, and when advantageously
a stepped turbine which is provided with radial-flow wheels is
employed as the turbine.
[0106] The second portion of the inventive heat pump advantageously
further comprises the controller 1112 so as to utilize the
electrical current generated at the output line 1108. Depending on
the implementation, the current may be directly utilized to drive
the dynamic-type compressor 16. Alternatively, the electrical
current generated by the turbine 1108 may also be fed into the
power supply network for a fee, while the current of the
dynamic-type compressor is also obtained from the power supply
network for money. This approach is economically useful, in
particular, when the fee obtained for feeding in current into the
power supply network is higher than the fee to be paid for current
obtained from the power supply network.
[0107] In addition, the current generated by the turbine may at
least partly be used for driving the water pump 1100.
[0108] An advantageous embodiment of the present invention will be
explained below in detail with reference to FIG. 2. The water
evaporator comprises an evaporation chamber 100 and a riser pipe
102, wherein ground water from a ground water reservoir 104 moves
upward into the evaporation chamber 100 in the direction of an
arrow 106. The riser pipe 102 leads to an expander 108 configured
to expand the relatively narrow pipe cross-section so as to provide
as large an evaporation area as possible. The expander 108 will
have the shape of a funnel, i.e. the shape of a rotation paraboloid
of any configuration. It may have round or square transitions. The
only thing that is critical is that the cross-section directed into
the evaporation chamber 100, or the area facing the evaporation
chamber 100, is larger than the cross-sectional area of the riser
pipe so as to improve the evaporation process. If one assumes that
about 1 l per second flows upward into the evaporation chamber
through the riser pipe, about 4 ml per second are evaporated within
the evaporator at a heating power of about 10 kW. The remainder
exits, cooled by about 2.5.degree. C., via the expander 108 and
ends up in a containment collection basin 110 within the
evaporation chamber. The containment collection basin 110 comprises
a drain 112, within which the quantity of 1 l per second, minus the
evaporated 4 ml per second, is dissipated again, advantageously
back to the ground water reservoir 104. For this purpose, a pump
114 or a valve for overflow control is provided. It shall be noted
that no active pumping is to be performed, since, due to gravity,
water will flow downward from the evaporator containment basin 110
into the ground water reservoir via a backflow pipe 113 if the pump
of the valve 114 is opened. The pump or the valve 114 thus ensures
that the water level within the containment basin does not rise to
too high a level or that no water vapor enters into the drain pipe
112, and that the evaporation chamber is also securely decoupled
from the situation at the "lower" end of the backflow pipe 113.
[0109] The riser pipe is arranged within a riser pipe basin 116
which is filled with water by a pump 118 which is advantageously
provided. The levels in 116 and 108 are connected to one another in
accordance with the principle of the communicating pipes, gravity
and the different pressures within 116 and 108 ensuring that the
water is transported from 116 to 108. The water level present in
the riser pipe basin 116 is advantageously arranged such that, even
with different air pressures, the level will never fall below the
inlet of the riser pipe 102 so as to prevent air from entering.
[0110] Advantageously, evaporator 10 comprises a gas separator
configured to remove at least part, e.g. at least 50% of a gas
dissolved in the water to be evaporated, from the water to be
evaporated, so that the removed part of the gas will not be sucked
in by the compressor via the evaporation chamber. Advantageously,
the gas separator is arranged to feed the removed part of the gas
to a non-evaporated water so that the gas is transported off by the
non-evaporated water. Dissolved gases may be oxygen, carbon
dioxide, nitrogen, etc. These gases evaporate mostly at a higher
pressure than water does, so that the gas separator may be arranged
downstream from the expander 108, so that oxygen etc., which has
been evaporated within the gas separator, will exit from the water
which has just not been evaporated yet, and will advantageously be
fed into the return pipe 113. Feeding-in is advantageously
performed at that location of the return pipe 113 at which the
pressure is so low that the gas is again taken along into the
ground water by the back-flowing water. Alternatively, the
separated gas may also be collected and be disposed of at specific
intervals or be constantly vented, i.e. released to the
atmosphere.
[0111] Typically, the ground water, sea water, river water, lake
water, the brine or any other naturally occurring aqueous solution
will have a temperature of between 8.degree. C. and 12.degree. C.
By lowering the temperature of 1 l of water by 1.degree. C., a
power of 4.2 kW may be generated. If the water is cooled by
2.5.degree. C., a power of 10.5 kW is generated. Advantageously, a
current of water with a current intensity depending on the heat
power, in the example one liter per second, flows through the riser
pipe.
[0112] If the heat pump works at a relatively high load, the
evaporator will evaporate about 6 ml per second, which corresponds
to a vapor volume of about 1.2 cubic meters per second. Depending
on the heating-system water temperature called for, the
dynamic-type compressor is controlled with regard to its
compression power. If a heating advance flow temperature of
45.degree. C. is desired, which is largely sufficient even for
extremely cold days, the dynamic-type compressor will have to
increase the pressure, which may have been generated at 10 hPa, to
a pressure of 100 hPa. If, on the other hand, an advance flow
temperature of, e.g., 25.degree. is sufficient for the floor
heating system, the compression that may be effected by the
dynamic-type compressor only will have a factor of 3.
[0113] The power generated is thus determined by the compressor
rating, i.e., on the one hand, by the compression factor, i.e. the
degree to which the compressor compresses and, on the other hand,
by the volume flow generated by the compressor. If the volume flow
increases, the evaporator will have to evaporate more, the pump 118
transporting more ground water into the riser pipe basin 116, so
that more ground water is fed to the evaporation chamber. On the
other hand, if the dynamic-type compressor provides a lower
compression factor, less ground water will flow from the bottom to
the top.
[0114] However, it shall also be noted here that it is advantageous
to control the passage of ground water through the pump 118.
According to the principle of the communicating pipes, the filling
level within container 116, or the displacement capacity of the
pump 118, establishes the amount of flow through the riser pipe.
Therefore, an increase in the efficiency of the plant may be
achieved, since the control of the flow is decoupled from the
suction power of the dynamic-type compressor.
[0115] No pump might be used for pumping the ground water from
below into the evaporation chamber 100. Rather, this occurs "by
itself". This automatic rise up to the evacuated evaporation
chamber also assists the fact that the negative pressure of 20 hPa
may be readily achieved. No evacuation pumps or the like might be
used for this purpose. Rather, only a riser pipe having a height of
more than 9 m may be used. Then a purely passive negative-pressure
generation is achieved. However, the negative pressure involved may
also be generated using a considerably shorter riser pipe, for
example when the implementation of FIG. 5a is employed. In FIG. 5a,
a considerably shorter "riser pipe" is shown. Converting high
pressure to the negative pressure is accomplished via a turbine
150, the turbine withdrawing energy from the working medium in this
context. At the same time, the negative pressure on the backflow
side is again returned to the high pressure, the energy involved in
this being supplied by a pump 152. The pump 152 and the turbine 150
are coupled to one another via a force coupling 154, so that the
turbine drives the pump, specifically using the energy that the
turbine has withdrawn from the medium. A motor 156 merely may still
be used for compensating for the losses which the system inevitably
will have, and to achieve the circulation, i.e. to bring a system
from its resting position into the dynamic mode depicted in FIG.
5a.
[0116] In the advantageous embodiment, the dynamic-type compressor
is configured as a radial-flow compressor with a rotatable wheel,
it being possible for the wheel to be a slow-speed radial-flow
wheel, a medium-speed radial-flow wheel, a half-axial flow wheel or
an axial flow wheel, or a propeller, as are known in the prior art.
Radial-flow compressors are described in "Stromungsmaschinen", C.
Pfleiderer, H. Petermann, Springer-Verlag, 2005, pp. 82 and 83.
Thus, such radial-flow compressors comprise, as the rotatable
wheel, the so-called center runner, the form of which depends on
the individual requirements. Generally, any dynamic-type
compressors may be employed, as are known as turbocompressors,
fans, blowers or turbocondensers.
[0117] In the advantageous embodiment of the present invention,
radial-flow compressor 16 is configured as several independent
dynamic-type compressors which may be controlled independently at
least with regard to their number of revolutions, so that two
dynamic-type compressors may have different numbers of revolutions.
Such an implementation is depicted in FIG. 6a, wherein the
compressor is configured as a cascade of n dynamic-type
compressors. At various locations downstream from the first
dynamic-type compressor, provision is advantageously made of one or
even more heat exchangers, for example for heating processed water,
which are designated by 170. These heat exchangers are configured
to cool the gas which has been heated up (and compressed) by a
preceding dynamic-type compressor 172. Here, overheating enthalpy
is sensibly exploited to increase the efficiency factor of the
entire compression process. The cooled gas is then compressed
further using one or several downstream compressors, or is directly
fed to the liquefier. Heat is extracted from the compressed water
vapor for heating, e.g., processed water to higher temperatures
than, e.g., 40.degree. C. However, this does not reduce the overall
efficiency factor of the heat pump, but even increases it, since
two successively connected dynamic-type compressors with gas
cooling connected in between, having a longer useful life achieve
the useful gas pressure within the liquefier due to the reduced
thermal load and while needing less energy than if a single
dynamic-type compressor without gas cooling were present.
[0118] FIG. 2 further depicts the components 1100, 1102, 1106 of
the second heat pump portion, the energy that may be used for the
evaporation within the evaporator 1102 no longer coming--in
contrast to ground water--from a medium having a low temperature,
but from a medium having a very high temperature, namely, e.g.,
from the waste gas stream of a burner, or a heat dissipation of a
solar collector.
[0119] It shall particularly be noted in this context that in the
northern latitudes, solar collectors generate high efficiencies
particularly in the transition times between summer and winter
between winter and summer, which is all the more true if the solar
collectors are operated not only for heating processed water, but
also for supporting the heating system. In the middle of summer,
the solar collectors generate a very large amount of warm water.
However, in the middle of summer, the demand is not particularly
high, so that the capacity of typical solar collectors is not
exploited in an optimum manner in the middle of summer, since the
entire supply of energy generated by a solar collector cannot be
stored, or can only be stored at very high expense, namely when
huge hot-water tanks are provided. In accordance with the
invention, this problem is now addressed in that the solar
collector is no longer used for heating water, but for evaporating
highly pressurized water. The high temperatures that may be used
for this are achieved particularly well in the middle of summer, in
particular, but are not available in winter. However, it is
possible also in summer to generate electrical energy with a high
efficiency factor using a solar collector, namely in the form of
the energy provided by the turbine. If a heat sink is used at all
for operating this cycle, the heating advance flow and/or the
heating backflow may no longer be input into heating a building,
but may be coupled, for example, to a heat sink in the ground so as
not to allow the liquefier temperature to rise to an excessive
level.
[0120] Thus, energy may also be generated in an optimum fashion in
summer by means of a solar collector, specifically valuable
electrical energy which may be output to the power supply network
and which additionally need not be stored by a private household,
but may be output to the power supply network in return for high
fees.
[0121] In winter, when the solar collector does not provide the
useful high temperatures for water evaporation, this may readily be
generated by operating a burner, which is employed anyhow by many
households for reasons of comfort, e.g. in the form of a
wood-burning fireplace. In addition to heating comfort, there is
now also a "financial" comfort, since due to the water evaporation
at a high temperature due to the burning of fuels, the current
generated may be used for driving the dynamic-type compressor of
the actual heating system of the building in the form of the first
portion of the heat pump, or may be used for obtaining a power
supply network feed, and thus to obtain a financial output. It is
not only in summer, but also in winter that the inventive concept
thus provides for a reduction of the power consumption costs, and,
thus, of the heating costs; due to the generation of electrical
current by water evaporation instead of photovoltaics, heating may
be obtained at almost no cost, from an overall perspective, when
solar radiation is sufficient, since electricity feed-in in summer
may even cut down on the power consumption, in terms of cost, in
winter.
[0122] Advantageous implementations of, in particular, the first
portion of the heat pump will be addressed below.
[0123] The cascaded dynamic-type compressors operated independently
are advantageously controlled by a controller 250 which maintains,
on the input side, a target temperature within the heating circuit
and, as the situation may be, also an actual temperature within the
heating circuit. Depending on the target temperature desired, the
number of revolutions of a dynamic-type compressor which is
arranged upstream in the cascade and is referred to by n1, by way
of example, and the number of revolutions n2 of a dynamic-type
compressor which is arranged downstream in the cascade are changed
such as is depicted by FIG. 6b. If a higher target temperature is
input into the controller 250, both numbers of revolutions are
increased. However, the number of revolutions of the dynamic-type
compressor arranged upstream, which is referred to by n1 in FIG.
6b, is increased with a smaller gradient than the number of
revolutions n2 of a dynamic-type compressor arranged downstream in
the cascade. This results in that--when the ratio n2/n1 of the two
numbers of revolutions is plotted--a straight line having a
positive slope results in the diagram of FIG. 6b.
[0124] The point of intersection between the numbers of revolutions
n1 and n2 which are individually plotted may occur at any point,
i.e. at any target temperature, or may not occur, as the case may
be. However, it is generally advantageous to increase a
dynamic-type compressor arranged closer to the liquefier within the
cascade more highly, with regard to its number of revolutions, than
a dynamic-type compressor arranged upstream in the cascade, should
a higher target temperature be desired.
[0125] The reason for this is that the dynamic-type compressor
arranged downstream in the cascade may process further already
compressed gas which has been compressed by a dynamic-type
compressor arranged upstream in the cascade. In addition, this
ensures that the vane angle of vanes of a radial-flow wheel, as is
also discussed with reference to FIGS. 6c and 6d, is positioned as
favorably as possible with regard to the speed of the gas to be
compressed. Thus, the setting of the vane angle only consists in
optimizing a compression of the in-flowing gas which is as low in
eddies as possible. The further parameters of the angle setting,
such as gas throughput and compression ratio, which otherwise would
have enabled a technical compromise in the selection of the vane
angle, and thus would have enabled an optimum efficiency factor at
a target temperature only, are brought, in accordance with the
invention, to the optimum operating point by the independent
revolutions control, and therefore have no longer any influence on
the selection of the vane angle. Thus, an optimum efficiency factor
results despite an fixedly set vane angle.
[0126] In this regard, it is advantageous, in addition, for a
dynamic-type compressor which is arranged more in the direction of
the liquefier within the cascade to have a rotational direction of
the radial-flow wheel which is opposed to the rotational direction
of the radial-flow wheel arranged upstream in the cascade. Thus, an
almost optimum entry angle of the vanes of both axial flow wheels
in the gas stream may be achieved, such that a favorable efficiency
factor of the cascade of dynamic-type compressors occurs not only
within a small target temperature range, but within a considerably
broader target temperature range of between 20 and 50 degrees,
which is an optimum range for typical heating applications. The
inventive revolutions control and, as the case may be, the use of
counter-rotating axial flow wheels thus provides an optimum match
between the variable gas stream at a changing target temperature,
on the one hand, and the fixed vane angles of the axial flow
wheels, on the other hand.
[0127] In advantageous embodiments of the present invention, at
least one or advantageously all of the axial flow wheels of all
dynamic-type compressors are made of plastic having a tensile
strength of more than 80 MPa. An advantageous plastic for this
purpose is polyamide 6.6 with inlaid carbon fibers. This plastic
has the advantage of having a high tensile strength, so that axial
flow wheels of the disturbance compressors may be produced from
this plastic and may nevertheless be operated at high numbers of
revolutions.
[0128] Advantageously, axial flow wheels are employed in accordance
with the invention, as are shown, for example, at reference numeral
260 in FIG. 6c. FIG. 6c depicts a schematic top view of such a
radial-flow wheel, while FIG. 6d depicts a schematic
cross-sectional view of such a radial-flow wheel. As is known in
the prior art, a radial-flow wheel comprises several vanes 262
extending from the inside to the outside. The vanes fully extend
toward the outside, with regard to axis 264 of the radial-flow
wheel, from a distance of a central axis 264, the distance being
designated by rW. In particular, the radial-flow wheel includes a
base 266 as well as a cover 268 directed toward the suction pipe or
toward a compressor of an earlier stage. The radial-flow wheel
includes a suction opening designated by r1 to suck in gas, this
gas subsequently being laterally output by the radial-flow wheel,
as is indicated at 270 in FIG. 6d.
[0129] When looking at FIG. 6c, the gas in the rotational direction
before from the vane 262 has a higher relative speed, while it has
a reduced speed behind from the vane 262. However, for high
efficiency and a high efficiency factor it is advantageous for the
gas to be laterally ejected from the radial-flow wheel, i.e. at 270
in FIG. 6d, everywhere with as uniform a speed as possible. For
this purpose, it is desirable to mount the vanes 262 as tightly as
possible.
[0130] For technical reasons, however, it is not possible to mount
vanes which extend from the inside, i.e. from the radius rW, to the
outside as tightly as possible, since the suction opening having
the radius r1 then will become more and more blocked.
[0131] It is therefore advantageous, in accordance with the
invention, to provide vanes 272 and 274 and 276, respectively,
which extend over less than the length of vane 262. In particular,
the vanes 272 do not extend from rW fully to the outside, but from
R1 to the exterior with regard to the radial-flow wheel, R1 being
larger than rW. By analogy therewith, as is depicted by way of
example in FIG. 6c, vanes 274 only extend from R2 to the exterior,
whereas vanes 276 extend only from R3 to the outside, R2 being
larger than R1, and R3 being larger than R2.
[0132] These ratios are schematically depicted in FIG. 6d, a double
hatching, for example within area 278 in FIG. 6d, indicating that
there are two vanes in this area which overlap and are therefore
marked by the double-hatched area. For example, the hatching from
the bottom left to the top right, shown in area 278, designates a
vane 262 extending from rW to the very outside, whereas the
hatching extending from the top left to the bottom right in area
278 indicates a vane 272 which extends only from r1 to the outside
in relation to the radial-flow wheel.
[0133] Thus, at least one vane is advantageously arranged between
two vanes extending further to the inside, said one vane not
extending so far toward the inside. This results in that the
suction area is not plugged, and/or that areas having a smaller
radius are not too heavily populated with vanes, whereas areas
having a larger radius are more densely populated with vanes, so
that the speed distribution of the exiting gas which exists at the
output of the radial-flow wheel, i.e. where the compressed gas
leaves the radial-flow wheel, is as homogeneous as possible. With
the inventive advantageous radial-flow wheel in FIG. 6c, the speed
distribution of the exiting gas is particularly homogeneous at the
outer periphery, since the distance of vanes accelerating the gas
and due to the "stacked" arrangement of the vanes is considerably
smaller than in a case where, for example, only vanes 262 are
present which extend from the very inside to the very outside, and
thus may have a very large distance at the outer end of the
radial-flow wheel, the distance being considerably larger than in
the inventive radial-flow wheel as is depicted in FIG. 6c.
[0134] It shall be noted at this point that the relatively
expensive and complicated shape of the radial-flow wheel in FIG. 6c
may be produced in a particularly favorable manner by plastic
injection molding, it being possible, in particular, to simply
achieve that all vanes, including the vanes which do not extend
from the very inside to the very outside, i.e. vanes 272, 274, 276,
are fixedly anchored, since they are connected both to the cover
268 and to the base 266 of FIG. 6d. The use of plastic in
particular with the plastic injection molding technique enables
production of any shapes desired in a precise manner and at low
cost, which is not readily possible or is possible only at very
high expense, or is possibly not even possible at all, with axial
flow wheels made of metal.
[0135] It shall be noted at this point that very high numbers of
revolutions of the radial-flow wheel are advantageous, so that the
acceleration acting upon the vanes takes on quite considerable
values. For this reason it is advantageous that particularly the
shorter vanes 272, 274, 276 be fixedly connected not only to the
base but also to the cover, such that the radial-flow wheel may
readily withstand the accelerations occurring.
[0136] It shall also be noted in this context that the use of
plastic is favorable also because of the superior impact strength
of plastic. For example, it cannot be ruled out that ice crystals
or water droplets will hit the radial-flow wheel at least of the
first compressor stage. Due to the large accelerations, very large
impact forces result here which plastics having sufficient impact
strength readily withstand. In addition, the liquefaction within
the liquefier advantageously occurs on the basis of the cavitation
principle. Here, small vapor bubbles collapse, on the basis of this
principle, within a volume of water. From a microscopic point of
view, quite considerable speeds and forces arise there which may
lead to material fatigue in the long run, but which can be readily
controlled when using a plastic having sufficient impact
strength.
[0137] The compressed gas output by the last compressor 174, i.e.
the compressed water vapor, is then fed to the liquefier 18 which
may be configured such as is depicted in FIG. 2, but which is
advantageously configured such as is shown in FIG. 3a. The
liquefier 18 contains volume of water 180 and advantageously a
volume of steam 182 which may be as small as is desired. The
liquefier 18 is configured to feed the compressed vapor into the
water of the water volume 180, so that a condensation immediately
results where the steam enters into the liquid, as is schematically
drawn at 184. To this end, it is advantageous for the gas supply to
have an expansion area 186, such that the gas is distributed over
as large an area as possible within the liquefier water volume 180.
Typically, because of the temperature layers, the highest
temperature within a water tank will be at the top, and the coolest
temperature will be at the bottom. Therefore, the heating advance
flow will be arranged, via a floater 188, as close to the surface
of the water volume 180 as possible so as to extract the warmest
water from the liquefier water volume 180. The heating backflow is
fed to the liquefier at the bottom, so that the vapor to be
liquefied comes in contact with water which is as cool as possible
and which moves, due to the circulation using a heating circulating
pump 312, again from the bottom in the direction of the steam-water
border of the expander 186.
[0138] The embodiment in FIG. 2, wherein only a simple circulating
pump 312 exists, is sufficient when the liquefier is arranged in a
building such that the areas to be heated are located below the
liquefier, so that, due to gravitation, all heating pipes have a
pressure which is larger than that in the liquefier.
[0139] By contrast, FIG. 5b shows an implementation of a connection
of a heating line to the liquefier having a turbine/pump
combination if the liquefier is to be arranged at a height lower
than that of the heating line, or if a conventional heating which
involves a higher pressure is to be connected. Thus, if the
liquefier is to be arranged at a lower height, i.e. below an area
to be heated, and/or below the heating line 300, the pump 312 will
be configured as a driven pump as is shown at 312 in FIG. 5b. In
addition, a turbine 310 will be provided within the heating
backflow 20b for driving the pump 312, the turbine 310 being wired
to the pump 312 via a force coupling 314. The high pressure will
then be present within the heating system, and the low pressure
will be present within the liquefier.
[0140] Since the water level within the liquefier would rise more
and more due to the vapor being constantly introduced into the
liquefier, the drain 22 is provided, via which, e.g., about 4 ml
per second may also drain off for the water level within the
liquefier to essentially not change. To this end, a drain pump, or
a drain valve, 192 for pressure regulation is provided, such that
without pressure loss, the useful amount of, e.g., 4 ml per second,
i.e. the quantity of water vapor which is fed to the liquefier
while the compressor is running, is drained off again. Depending on
the implementation, the drain may be introduced into the riser pipe
as is shown at 194. Since all kinds of pressures between one bar
and the pressure existing within the evaporation chamber are
present along the riser pipe 102, it is advantageous to feed in the
drain 22 into the riser pipe at that location 194 where roughly the
same pressure exists as it exists downstream from the pump 192, or
valve 192. Then, no work has to be done to re-feed the drain water
to the riser pipe.
[0141] In the embodiment shown in FIG. 2, one operates completely
without any heat exchanger. The ground water is thus evaporated,
the vapor is then liquefied within the liquefier, and the liquefied
vapor is eventually pumped through the heating system and re-fed to
the riser pipe. However, since only a (very small) part of, rather
than all of, the quantity of water flowing through the riser pipe
is evaporated, water which has flown through the floor heating
system is thus fed to the ground water. If something like this is
prohibited according to communal regulations, even though the
present invention entails no contamination whatsoever, the drain
may also be configured to feed the amount of 4 ml per second, which
corresponds to roughly 345 l per day, to the sewage system. This
would ensure that no medium which has been present within any
heating system of any building is directly fed back into the ground
water.
[0142] However, the backflow 112 from the evaporator may be fed to
the ground water without any problems, since the water flowing back
there only was in contact with the riser pipe and the return line,
but has not exceeded the "evaporation boundary" between the
evaporation expander 108 and the output to the dynamic-type
compressor.
[0143] It shall be noted that in the embodiment shown in FIG. 2,
the evaporation chamber as well as the liquefier, or the vapor
chamber 182 of the liquefier, may be sealed off. As soon as the
pressure within the evaporation chamber exceeds the mark that may
be used for the water being pumped through the riser pipe to
evaporate, the heat pump process comes to a "standstill".
[0144] In the following, reference shall be made to FIG. 3a which
represents an advantageous embodiment of the liquefier 18. The feed
line 198 for compressed vapor is positioned within the liquefier
such that the vapor may exit into this water volume just below the
surface of the liquefier water volume 180. For this purpose, the
end of the vapor supply line comprises nozzles arranged around the
circumference of the pipe, through which the vapor may exit into
the water. For the mixing which occurs to be as thorough as
possible, i.e. for the vapor to come into contact with water as
cold as possible to liquefy as fast and efficiently as possible, an
expander 200 is provided. This expansion is arranged within the
liquefier water volume 180. At its narrowest point, it has a
circulating pump 202 configured to suck in cold water at the bottom
of the liquefier and to displace it, by means of the expander,
toward a flow which is directed upward and becomes broader. This is
intended to cause as large quantities as possible of the vapor
entering into the liquefier water 180 to contact water which is
provided by the circulating pump 202 and is as cold as
possible.
[0145] In addition, it is advantageous to provide, around the
liquefier, a sound insulation 208 which may be configured in an
active or a passive manner. A passive sound insulation will
insulate the frequencies of the sound generated by the liquefaction
as well as possible, similar to thermal insulation. It is equally
advantageous to subject the other components of the system to the
sound insulation.
[0146] Alternatively, the sound insulation may also be configured
to be active, in which case it would have, for example, a
microphone for sound measurement, and would trigger, in response
thereto, a sound countereffect, such as to cause an outer liquefier
wall etc. to vibrate with, e.g., piezoelectric means.
[0147] The embodiment shown in FIG. 3a is somewhat problematic in
that the liquid 180 located within the liquefier will enter into
the pipe 198, within which otherwise a compressed vapor is present,
when the heat pump is powered down. In one implementation, a
backflow valve may be provided within line 198, for example near
the output of the line from the liquefier. Alternatively, the line
198 may be directed upward, specifically so far upward that no
liquid flows back into the compressor when the compressor is
switched off. When the compressor is powered up again, the water
from the vapor line 198 will initially be pressed into the
liquefier by the compressed vapor.
[0148] Not until a sufficient portion of the water has been removed
from the line 198 will a vapor be made to condensate within the
liquefier. An embodiment of such a type thus has a certain delay
time which is useful until the water volume 180 is heated up again
by the compressed vapor. In addition, the work useful for removing
the water which has entered into the line 198 from the line 198
again is no longer retrievable and is thus "lost" with regard to
the heating system, such that small-scale losses in terms of the
efficiency factor may have to be accepted.
[0149] An alternative embodiment which overcomes this problem is
shown in FIG. 3b. Unlike in FIG. 3a, the compressed vapor is now
not fed within a pipe below the water level within the liquefier.
Instead, the vapor is "pumped", as it were, into the liquid within
the liquefier from the surface. For this purpose, the liquefier
includes a nozzle plate 210 comprising nozzles 212 which project in
relation to the plane of the nozzle plate 210. The nozzles 212
extend below the water level of the water volume 180 in the
liquefier. The recessed portions between two nozzles, shown at 214
in FIG. 3b, by contrast extend above the water level of the water
volume 180 within the liquefier, so that the water surface of the
liquefier water, the water surface being interrupted by a nozzle,
is located between two nozzles. The nozzle 212 has nozzle openings
through which the compressed vapor which spreads from the line 198
within the vapor volume 182 may enter into the liquefier water, as
is schematically shown by arrows 216.
[0150] If, in the implementation of FIG. 3b, the compressor is
powered down, this will result in that the liquid enters into the
nozzles 212 of the nozzle plate 210 to a small extent only, so that
very little work may be done in order to press the water out from
the nozzles again when the heat pump is powered up again. At any
rate, the expander 200 ensures that, due to being fed through the
expander, the liquid transported upward by the pump 202 is as cold
as possible and comes into contact with the warm vapor. Then the
warm water will either immediately enter into the advance flow 20a,
or it will spread within the water volume over the expander edge,
as is depicted by an arrow 218, so that a temperature
stratification which is disturbed to as small an extent as
possible, in particular because of the shape of the expander, will
occur within the liquefier outside the expander.
[0151] The flow rate present at the edge of the expander, i.e.
where arrow 218 is indicated, is considerably lower than in the
center. It is advantageous to operate the liquefier as a
temperature layer storage such that the heat pump and, in
particular, the compressor need not run without interruption, but
may run only when there is a need, as is also the case for normal
heating installations operating, for example, with an oil
burner.
[0152] FIG. 3c shows a further advantageous implementation of the
liquefier in a schematic form. In particular, the liquefier
comprises a gas separator 220 coupled to the gas volume 182 within
the liquefier. Any gas arising within the liquefier, such as oxygen
or another gas which may leak within the liquefier, collects within
the gas-separator container 220. By actuating a pump 222,
advantageously at certain intervals, since permanent gas evacuation
might not be used due to the small quantity of gas developing, this
gas may then be pumped into the atmosphere. Alternatively, the gas
may also be docked into the backflow 112 or 113 of FIG. 2 again, so
that the gas is again brought back into the ground water reservoir,
along with the ground water flowing back, where it will again be
dissolved within the ground water, or will merge into the
atmosphere when it enters into the ground water reservoir.
[0153] Since the inventive system operates with water, no gases
will develop, even with a high gas leakage, which have not already
been dissolved within the ground water previously, so that the gas
separated off entails no environmental problems whatsoever. It
shall again be emphasized that, due to the inventive dynamic-type
compressor compression and due to the use of water as the working
fluid, there will be no contamination or soiling by synthetic
coolants or by oil, due to an oil cycle, at any point. As the
working medium, the inventive system at any point has water or
vapor, which is at least as clean as the original ground water, or
is even cleaner than the ground water due to the evaporation within
the evaporator, since the water is distilled water once the
compressed vapor has been liquefied again within the liquefier.
[0154] In the following, an advantageous embodiment of the
evaporator will be depicted with reference to FIG. 4a so as to
advantageously employ the liquefier drain to accelerate the
evaporation process. For this purpose, the drain, which, as one
knows, has the temperature of the heating system backflow, i.e. has
a much higher temperature than the ground water pumped from the
earth, is passed through the expander 108 of the evaporator, so
that the wall of the drain pipe 204 acts as a nucleus for nucleate
boiling. Thus, a substantially more efficient vapor is generated by
the evaporator than if no such nucleating action were provided. In
addition, it is advantageous to configure the wall of the drain
pipe 204, at least within the expander, to be as structured as
possible, as is depicted at 206, to improve the nucleation for the
nucleate boiling even more. The rougher the surface of the drain
pipe 204, the more nuclei will be generated for nucleate boiling.
It shall be noted that the flow through the drain pipe 22 is only
very low, since what is dealt with here is only the 4 ml per second
which are fed to the liquefier in one mode of operation.
Nevertheless, the considerably more efficient nucleate boiling may
be caused already with this small amount and because of the
temperature, which is relatively high as compared to the ground
water, so as to reduce the size of the evaporator while maintaining
the efficiency of the heat pump.
[0155] To accelerate the evaporation process, alternatively or
additionally, an area of the evaporator which has water which is to
be evaporated located thereon, i.e. the surface of the expander or
a part thereof, may be configured from a rough material to provide
nuclei for nucleate boiling. Alternatively or additionally, a rough
grate may also be arranged (close to) below the water surface of
the water to be evaporated.
[0156] FIG. 4b shows an alternative implementation of the
evaporator. While the drain in FIG. 4a has been employed merely as
a "flow-through" assistance of the nucleate formation for efficient
evaporation, and, as has been depicted on the left-hand side in the
picture in FIG. 4a, the drain is drained off once it has passed
through the evaporator, the drain in FIG. 4b is itself used for
reinforcing the nucleate formation. For this purpose, the liquefier
drain 22 of FIG. 2 is connected to a nozzle pipe 230, possibly via
a pump 192 or, if conditions permit, without a pump, the nozzle
pipe 230 having a seal 232 on one end and having nozzle openings
234. The warm liquefier water drained from the liquefier via drain
22 at a rate of, for example, 4 ml per second is now fed into the
evaporator. On its way to a nozzle opening 234 within the nozzle
pipe 230, or immediately at the exit of a nozzle, it will already
evaporate, as it were, below the water surface of the evaporator
water because of the pressure which is too low for the temperature
of the drain water.
[0157] The vapor bubbles forming there will immediately act as
boiling nuclei for the evaporator water which is pumped via the
inflow 102. Thus, efficient nucleate boiling may be triggered
within the evaporator without any major additional measures being
taken, this triggering existing, similar to FIG. 4a, because of the
fact that the temperature near the rough area 206 in FIG. 4a or
near a nozzle opening 234 is already so high that, given the
existing pressure, evaporation will immediately take place. This
evaporation forces the generation of a small vapor bubble which, if
the conditions are favorably selected, will have a very high
probability of not collapsing again, but of developing into a vapor
bubble which goes to the surface and which, once it has entered
into the vapor volume within the evaporation chamber, will be
sucked off by the compressor via the suction pipe 12.
[0158] The embodiment shown in FIG. 4b involves the liquefier water
to be brought into the ground water cycle, since the medium exiting
the nozzle pipe 230 eventually will re-enter into the backflow 112
via the overflow of the evaporator, and will thus be made to
contact the ground water.
[0159] If there are water-regulatory provisions or any other
reasons why this is not admissible, the embodiment shown in FIG. 4c
may be employed. The warm liquefier water provided by the liquefier
drain 22 is introduced into a heat exchanger 236 at a rate of,
e.g., 4 ml per second to give off its heat to ground water which
has been branched off from the main ground water stream within line
102 via a branch line 238 and a branching-off pump 240. The
branched-off ground water will then essentially take on the heat of
the liquefier drain within the heat exchanger 236, so that
pre-heated ground water is introduced into the nozzle pipe 230, for
example at a temperature of 33.degree. C. so as to effectively
trigger or support the nucleate boiling within the evaporator by
means of the temperature which is high compared to the ground
water. On the other hand, the heat exchanger provides, via a drain
line 238, drain water which is cooled to a relatively high extent
and which is then fed to the sewage system via a drain pump 240. On
the basis of the combination of the branch line 238 and the
branching-off pump 240 and the heat exchanger 236, only ground
water is used in, or introduced into, the evaporator without said
ground water having been in contact with any other medium. Thus,
there is no water-regulatory relevance associated with the
embodiment shown in FIG. 4c.
[0160] FIG. 4d shows an alternative implementation of the
evaporator with edge feeding. Unlike in FIG. 2, here the expander
200 of the evaporator is arranged below the water level 110 within
the evaporator. This causes water to flow toward the center of the
expander "from outside" so as to be returned in a central line 112.
While the central line in FIG. 2 has served to feed the evaporator,
in FIG. 4d it now serves to drain off the non-evaporated ground
water. By contrast, the line 112 shown in FIG. 2 has served to
drain off non-evaporated ground water. In FIG. 4d, by contrast,
this line at the edge serves as a ground water feed.
[0161] FIG. 4e shows an advantageous implementation of the expander
200 as may be employed within the evaporator, or of the expander as
may also be employed, e.g., within the liquefier and as is shown,
for example, in FIG. 2 or FIG. 3a or 3b, respectively. The expander
is advantageously configured such that its small diameter
advantageously enters into the expander in the center of the
"large" expander area. This diameter of this inflow or drain (in
FIG. 4d) advantageously ranges between 3 and 10 cm and, in
particularly advantageous embodiments, between 4 and 6 cm.
[0162] The large diameter d2 of the expander ranges between 15 and
100 cm in advantageous embodiments, and is smaller than 25 cm in
particularly advantageous embodiments. The small configuration of
the evaporator is possible if efficient measures for triggering and
assisting nucleate boiling are employed, as has been explained
above. The small radius d1 and the large radius d2 have an area of
curvature of the expander located between them which is
advantageously configured such that within this area a laminar flow
results which is decreased from a fast flow rate, advantageously
within the range from 7 to 40 cm per second, to a relatively small
flow rate at the edge of the expander. Large discontinuities of the
flow rate, for example eddies within the area of the line of
curvature, or "bubbling effects" above the inflow, if the expander
is viewed from the top, are advantageously avoided since they may
possibly have a negative effect on the efficiency factor.
[0163] In particularly advantageous embodiments, the expander has a
shape which results in that the height of the water level above the
expander surface is smaller than 15 mm and is advantageously
between 1 and 5 mm. It is therefore advantageous to employ an
expander 200 configured such that in more than 50% of the area of
the expander, when viewed from the top, a water level exists which
is smaller than 15 mm. Thus, efficient evaporation may be ensured
across the entire area which is even increased, it terms of its
efficiency, when measures for triggering nucleate boiling are
used.
[0164] Thus, the inventive heat pump serves to efficiently supply
buildings with heat, and it no longer involves any working
substance which negatively affects the world climate. In accordance
with the invention, water is evaporated under very low pressure, is
compressed by one or several dynamic-type compressors arranged one
behind the other, and is again liquefied into water. The
transported energy is used for heating. In accordance with the
invention, use is made of a heat pump which advantageously
represents an open system. Here, open system means that ground
water or any other available aqueous medium carrying heat energy is
evaporated, compressed and liquefied under low pressure. The water
is directly used as the working substance. Thus, the energy
contained is not transmitted to a closed system. The liquefied
water is advantageously used directly within the heating system and
is subsequently supplied back to the ground water. To capacitively
decouple the heating system, it may also be terminated by a heat
exchanger.
[0165] The efficiency and usefulness of the present invention is
represented by means of a numerical example. If one assumes an
annual heating requirement of 30,000 kWh, in accordance with the
invention about maximally 3,750 kWh of electrical current may be
expended for operating the dynamic-type compressor to achieve this,
since the dynamic-type compressor need only provide about an eighth
of the entire amount of heat that may be useful.
[0166] The eighth results from the fact that a sixth needs to be
expended in the event of extreme cold only, and that, for example,
at transition temperatures such as in March or at the end of
October, the efficiency factor may rise to a value of more than 12,
so that, on average, a maximum of one eighth may be expended over
the year.
[0167] At electricity prices of about 10 eurocents per kWh, which
may be arrived at for electricity if one buys electricity for which
the power station need not guarantee that operation will be free
from interruptions, this roughly corresponds to annual costs of 375
euros. If one wants to generate 30,000 kWh using oil, one would
need about 4,000 l, which would correspond to a price of 2,800
euros on the basis of current oil prices, which are very unlikely
to fall in the future. In accordance with the invention, one can
therefore save 2,425 euros per annum! In addition, it shall also be
pointed out that in comparison with burning oil or gas for heating
purposes, up to 70% of the amount of CO2 released is saved by means
of the inventive concept.
[0168] To reduce the manufacturing cost and also to reduce the
maintenance and assembly costs, it is advantageous to configure the
housings of the evaporator, of the compressor and/or of the
liquefier and also, particularly, the radial-flow wheel of the
dynamic-type compressor, from plastic, and in particular from
injection molding plastic. Plastic is well suited since plastic is
corrosion-resistant with regard to water, and since, in accordance
with the invention, the maximum temperatures are advantageously
clearly below the deformation temperatures of employable plastics
compared to conventional heating systems. In addition, assembly is
particularly simple since negative pressure is present within the
system consisting of evaporator, compressor and liquefier. Thus,
substantially fewer requirements are placed on the sealings since
the entire atmospheric pressure assists in keeping the housings
leak-proof. Also, plastic is particularly well suited since at no
location in the inventive system are there high temperatures which
would involve the use of expensive special plastics, metal or
ceramic. By means of plastic injection molding, the shape of the
radial-flow wheel may also be optimized in any manner desired while
being manufactured in a simple manner and at low cost despite its
complicated shape.
[0169] Depending on the circumstances, the inventive method may be
implemented in hardware or in software. Implementation can be on a
digital storage medium, in particular a disk or CD, with
electronically readable control signals which may interact with a
programmable computer system such that the respective method is
performed. Generally, the invention thus also consists in a
computer program product with a program code, stored on a
machine-readable carrier, for performing the inventive method when
the computer program product runs on a computer. In other words,
the invention may thus be realized as a computer program having a
program code for performing the method when the computer program
runs on a computer.
[0170] In accordance with an embodiment of the present water pump,
same comprises, in the first portion, an evaporator 10, which may
be coupled to a heat source, a dynamic-type compressor 16
configured to consume electrical current, and the liquefier 18, the
heat source being dimensioned such that the working fluid
evaporates at the first pressure.
[0171] In an advantageous embodiment of the water pump, the
evaporator 100 is configured to evaporate water which is present in
the environment in the form of ground water, sea water, river
water, lake water or brine, and the liquefier 18 is configured to
feed liquefied water to the evaporator, to the soil or to a water
treatment plant.
[0172] In an advantageous embodiment of the water pump, the
compressor 16 is configured to compress the working vapor to a
working pressure higher than 25 hPa.
[0173] In an advantageous embodiment of the water pump, the
dynamic-type compressor is configured as a radial-flow
compressor.
[0174] In an advantageous embodiment of the water pump, the
evaporator 10 comprises a riser pipe 102 coupled to the evaporation
chamber 100, one end of the riser pipe 102 being connected to a
liquid-filled container 116 for the working liquid, and the other
end of the riser pipe 102 being connected to the evaporation
chamber 100 so that the evaporation pressure results within the
evaporation chamber 100 due to the effect of gravitation.
[0175] In an advantageous embodiment of the water pump, the riser
pipe 102 is configured to have a height of more than 8 m.
[0176] In an advantageous embodiment of the water pump, the
evaporator comprises a turbine 150, via which a pressure of an
upstreaming working fluid is reduced, and which extracts energy
from the working liquid in the process, the turbine 150 further
being operatively coupled to a pump 152 to bring a downstreaming
working liquid from the pressure present within the evaporation
chamber to the pressure of the upstreaming working fluid, the
operative coupling 154 being configured such that the pump 152 uses
at least part of the energy the turbine has extracted.
[0177] In an advantageous embodiment of the water pump, the
evaporator 10 comprises: an expander 108 which expands, within the
evaporation chamber, to at least three times a diameter of a feed
line to the evaporation chamber; a reception apparatus 110
configured to receive any working liquid overflowing over an edge
of the expander 108; and a drain means 112 configured to carry off
the overflowing working liquid.
[0178] In an advantageous embodiment of the water pump, the drain
means 112 is coupled to a flow control means 114, the flow control
means 114 being controllable to maintain a level of the overflowing
working liquid within the reception apparatus 110 within a
predefined range.
[0179] In an advantageous embodiment of the water pump, the
evaporator 10 comprises a gas separator configured to remove at
least part of a gas dissolved in the water to be evaporated from
the water to be evaporated, so that the removed part of the gas is
not sucked in by the compressor via the evaporation chamber.
[0180] In an advantageous embodiment of the water pump, the gas
separator is arranged to feed the removed part of the gas to
non-evaporated water so that the gas is transported off by the
non-evaporated water.
[0181] In an advantageous embodiment of the water pump, the
evaporator 10 comprises: an expander 200 which expands, within the
evaporation chamber, to at least three times a diameter of a drain
112 outside the evaporation chamber 100; a reception apparatus
configured to receive the working liquid fed to the evaporation
chamber; and an inflow means to supply the reception apparatus with
ground water; the expander being arranged within the evaporation
chamber such that working fluid flows off, over an edge of the
expander comprising a large diameter, to an area of the expander
comprising a low diameter, and from there via a drainage.
[0182] In an advantageous embodiment of the water pump, the
liquefier comprises a gas separator 220, 222 to drain off, from a
separator volume 220, any gas accumulating within the liquefier
which differs from water vapor.
[0183] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a drain 22 to drain off liquefied working
liquid, and the drain 22 comprises a portion 204 arranged within
the evaporator for providing a nucleating effect for a bubble
evaporation within the evaporator.
[0184] In an advantageous embodiment of the water pump, a portion
204 of a drain for water from the liquefier comprises a roughness
area 206 which has a surface roughness which is at least such that
a nucleating effect for a nucleate formation is increased as
compared with a smooth surface of the drain in the form of a common
pipe.
[0185] In an advantageous embodiment of the water pump, the drain
22 is coupled to a nozzle pipe 230 which comprises nozzle openings
234 to feed a working fluid located within the nozzle pipe 230 into
water which is to be evaporated and is located within the
evaporator, so as to provide a nucleating effect for a bubble
evaporation within the evaporator.
[0186] In an advantageous embodiment of the water pump, the
evaporator comprises a heat exchanger 236, a branch line 238 for
feeding the heat exchanger, and a heat-exchanger drain coupled to a
nozzle pipe 230 which comprises nozzle openings 234, and the heat
exchanger 236 being coupled, on the input side, to a liquefier
drain 22, so that a warmth of a liquid dispensed by the liquefier
drain 22 is transmitted to a working fluid fed to the nozzle pipe
230, so as to provide a nucleating effect for a bubble evaporation
within the evaporator.
[0187] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a drain 22 for draining off liquefied
working liquid, the drain being coupled, at a coupling position
194, to the riser pipe 102 or to a backflow pipe 113, where a
liquid pressure within the riser pipe or the backflow pipe 113 is
smaller than or equal to a pressure present at the drain 22.
[0188] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a drain 22 for draining off liquefied
working liquid, the drain being coupled, at a coupling position
194, to the riser pipe 102 or to a backflow pipe 113, a pressure
compensation means 192 being arranged between the drain 22 from the
liquefier 18 and the coupling position 194, the pressure
compensation means 192 being configured to control a pressure of
the water drained off from the liquefier 18 such that the water
will enter into the riser pipe 102 or into the backflow pipe
192.
[0189] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a drain 22 which comprises a pump 192
configured to increase a pressure of water drained off from the
liquefier to such a pressure that the water drained off may enter
into a sewage system or seep into soil on a property.
[0190] In an advantageous embodiment of the water pump, the
compressor 16 comprises a rotatable wheel which is configured as a
radial-flow wheel, a half-axial flow wheel, an axial flow wheel or
a propeller and may be driven to compress the working vapor.
[0191] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a liquefier chamber which may be filled up
at least partially with the liquefier water volume 180 and which is
further configured to maintain the water level above a minimum
level.
[0192] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a vapor supply line 198 coupled to an output
of the compressor 16, the vapor supply line being arranged within
the water volume 180 such that the vapor may enter into the water
volume 180 beneath a current water level.
[0193] In an advantageous embodiment of the water pump, the
liquefier 18 is configured to feed the compressed vapor to the
liquefier via a pipe arranged below a water surface within the
liquefier, the pipe comprising nozzle openings, so that the vapor
enters into a water volume within the liquefier via an area
determined by the nozzle openings.
[0194] In an advantageous embodiment of the water pump, the
liquefier comprises a nozzle plate 210 comprising projecting nozzle
openings 212, the nozzle plate being arranged within the liquefier,
with regard to the water volume 180, such that a water level within
the liquefier is positioned between a projecting nozzle opening 212
and the nozzle plate 210.
[0195] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a circulating pump 202 for circulating
liquefied working liquid to transport cold working liquid to a
condensating point or to transport heat to a cold working
liquid.
[0196] In an advantageous embodiment of the water pump, the
liquefier comprises a heating advance flow 20a and a heating
backflow 20b to the liquefier water volume 180.
[0197] In an advantageous embodiment of the water pump, a portion
of the heating backflow 20b has a turbine 310 arranged therein, via
which a high pressure within the heating system 300 is reduced to a
low pressure within a water volume 180 of the liquefier 180, and
the energy gained in the process is removed from the heating water,
the turbine 310 further being operatively coupled to the pump 312
to bring the heating water from the low pressure within the
liquefier to the high pressure within the heating system 300, the
operative coupling 314 being configured such that the pump 312 uses
at least part of the energy the turbine 310 has extracted.
[0198] In an advantageous embodiment of the water pump, the
liquefier 18 comprises a heat exchanger to decouple, in terms of
liquid, a heating system 300 and the liquefier.
[0199] In an advantageous embodiment of the water pump, the
liquefier 18 comprises an expander 200 comprising a narrow opening
and a wide opening, the expander being arranged within the
liquefier such that a circulating pump 202 is arranged within the
narrow opening, and the compressed vapor may be fed to the wide
opening 198.
[0200] In an advantageous embodiment of the water pump, the
compressor 16 is configured by several dynamic-type compressors
arranged one behind the other to compress the working vapor to an
intermediate pressure by a first dynamic-type compressor 172, and
to compress the working vapor to the working pressure by a last
dynamic-type compressor 174.
[0201] In an advantageous embodiment of the water pump, at least
two dynamic-type compressors arranged one behind the other comprise
axial flow wheels driven with rotational directions directed in a
manner opposed to one another.
[0202] In an advantageous embodiment of the water pump, one or
several heat exchangers 170 are arranged downstream from a first
dynamic-type compressor 172 or a further dynamic-type compressor
174 so as to withdraw heat from the working vapor and to heat water
therewith.
[0203] In an advantageous embodiment of the water pump, the heat
exchanger is configured to reduce the temperature of the working
vapor to a temperature, at a maximum, which is higher than a
temperature prior to a preceding compressor stage 172.
[0204] In an advantageous embodiment of the water pump, same
further comprises a sound insulation 208 configured such that
noises within the liquefier, the evaporator or the compressor are
damped by at least 6 dB.
[0205] In an advantageous embodiment of the water pump, same
comprises: a control 250 for maintaining a target temperature, for
detecting an actual temperature and for controlling the compressor
16 to increase an output pressure or an output volume of the
compressor if the target temperature is higher than the actual
temperature, and to reduce the output pressure or the output volume
if the target temperature is lower than the actual temperature.
[0206] In an advantageous embodiment of the water pump, the at
least the evaporation chamber, a housing of the compressor or a
housing of the liquefier, or a radial-flow wheel of the
dynamic-type compressor are made of plastic.
[0207] In an advantageous embodiment of the water pump, the
dynamic-type compressor 16 comprises a radial-flow compressor
comprising a radial-flow wheel 260 which comprises a plurality of
vanes 262, 272, 274, 276 extending from one or several inner radii
to one or several outer radii, the vanes extending to the outside,
with regard to the radial-flow wheel, from different radii R1, R2,
R3, r1 of the radial-flow wheel.
[0208] In an advantageous embodiment of the water pump, the at
least one vane 272 is arranged between two vanes 262 extending to
the outside, with regard to the radial-flow wheel 260, from a
radius rW, the at least one vane 272 extending to the outside, with
regard to the radial-flow wheel 260, from a larger radius R1.
[0209] In an advantageous embodiment of the water pump, the
radial-flow wheel 260 comprises a base 266 and a cover 268, at
least one vane 272 of the radial-flow wheel 260 which extends to
the outside from a larger radius R1 than another vane 262 being
integrally connected both to the cover 268 and to the base 266.
[0210] In an advantageous embodiment of the water pump, a
temperature of the water, which is compressed in the compression
step, is lower than 80.degree. C., and a temperature of the vapor,
which is generated in the evaporating step, is higher than
120.degree. C.
[0211] In an advantageous embodiment of the computer program
comprising a program code for performing the method, the computer
program runs on an arithmetic unit.
[0212] While this invention has been described in terms of several
embodiments, there are alterations, permutations, and equivalents
which fall within the scope of this invention. It should also be
noted that there are many alternative ways of implementing the
methods and compositions of the present invention. It is therefore
intended that the following appended claims be interpreted as
including all such alterations, permutations and equivalents as
fall within the true spirit and scope of the present invention.
* * * * *